A Pennsylvania psychiatric patient has been arraigned on charges including murder and attempted murder for allegedly shooting his caseworker in the head in a hospital office and then engaging in a gun battle with a doctor who tried to subdue him.

The patient, Richard Plotts, 49, was arraigned late Saturday night in his bed at the Hospital of the University of Pennsylvania, where he is being treated for his wounds and is under police guard, a spokeswoman for the Delaware County district attorney's office said.

Delaware County District Attorney Jack Whelan told ABC station WPVI-TV in Philadelphia that police seized two guns and a computer from Plotts' home in Clifton Heights this weekend.

Plotts is accused of opening fire inside the wellness center of Mercy Fitzgerald Hospital in Darby Borough just after 2 p.m. Thursday.

Police told WPVI that they believe Plotts went to his appointment intending to kill his psychiatrist, Dr. Lee Silverman. They said Plotts was angry because the hospital posted a sign declaring the building a "gun-free zone."

Plotts was inside Silverman's office for a scheduled appointment Thursday when he suddenly pulled a gun out of his waistband and shot his caseworker, Theresa Hunt, in the head at point-blank range, police said. Hunt was killed instantly.

Silverman dove to the floor, pulled a semi-automatic pistol out his pocket and had a furious close range gun battle with Plotts, who police said fired at least 10 rounds. The doctor, who was using a chair for protection, aimed his gun at Plotts and fired until it was empty, Whelan said Friday.

The doctor, who was grazed in the head and wounded in the thumb while covering his face, was able to get out of the office, unaware that he had struck Plotts three times.

According to Whelan, caseworker John D'Alonzo heard the shooting and called 911. He then climbed through a window into Silverman's office because the door was locked and "engaged in a wrestling match with Mr. Plotts," getting him on the ground. Whelan called D'Alonzo's actions "nothing short of heroic." Dr. Jeffrey Dekret helped D'Alonzo wrestle the gun away from Plotts and hold him for police, Whelan said.

Whelan said that D'Alonzo "believed Plotts was trying to reload." The prosecutor said Plotts had another 39 bullets.

"If it wasn't for the heroic actions" of Silverman and Dalonzo, "we believe he (Plotts) was going to reload that revolver and continue to fire," Whelan said.

Silverman has a license to carry a concealed weapon, Whelan said, and state policy says that it is legal to have a concealed weapon in a home or office, although hospital policy bars anyone except on-duty law enforcement officers from carrying weapons on campus, a Mercy Health System spokeswoman told the Associated Press.

"I believe it was his practice for his own self protection to carry a firearm," Whelan said.

The prosecutor said that had the doctor not had a gun and fired back, "he would probably not be alive today."

Plotts had a history of violence with arrests for simple assault and a federal bank robbery as well as illegal firearms possession.

Plotts did not have a license for the gun that he used. It was not clear whether he had a lawyer.